<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>outline方案</title>
</head>
<style>
	.outline{
		background-color: #333;
		width: 400px;
		height: 400px;
		margin: 50px;
		border: 1px #fff dashed;
		outline: 10px #333 solid;
	}
</style>
<body>
	<div class="outline"></div>
</body>
</html>